Better defaults for EventBuilder
Remove passing of smrt_config to handler.
Changes to EventBuilder

- Now externally configurable
- Using an explicit 'not_before' property for defining how old an event
  can be before we drop it.
Moving configuration of EventBuilder to handlers
EventBuilder now created by the Handler
No longer checking memory requirements

- It's not nescessary to check for the amount of available memory, as we
  no longer need that much memory.
Simplified definition of Handlers
Refactored Decoders, introduction of custom handlers
Reverted to default handler